“…the data [literature review] proves that there is no consensus on the meaning of PM. After extracting and analyzing the definitions of PM, we found 1459 different ends and 1025 different means.”

Schleidgen S, Klingler C, Bertram T, Rogowski W, Marckmann G: What is personalized medicine: sharpening a vague term based on a systematic literature review. BMC Medical Ethics 2013, 14(1):55.
http://www.biomedcentral.com/1472-6939/14/55

The authors’ own definition, at the end of their review is this:

“PM seeks to improve tailoring and timing of preventive and therapeutic measures by utilizing biological information and biomarkers on the level of molecular disease pathways, genetics, proteomics as well as metabolomics”